Engine safety switch



Sept. 9, 1958 Filed Dec. 3, i956 F. w. MURPHY ENGINE SAFETY SWITCH 2 Sheets-Sheet 1 INVENTOR ENMur vk ATTORNEY? sept- 9, 1958 F. w. MURPHY ENGINE SAFETY SWITCH Filed Dec. 5, 1956 2 Sheets-Sheet 2 iilhk INVENTOR I WMQ r v A 3 BY MM ATTORNEYS 'Patented Sept. 9, 1958 ENGINE SAFETY SWITCH Frank W. Murphy, Tulsa, Okla. Application December 3, 1956, Serial No. 625,946 2 Claims. (Cl. 200-56) The present invention relates to engine safety switches, and more particularly to such switches for interrupting. the ignition circuit in response to excess engine speeds.

'The primary object of the invention is to provide an engine safety switch correlated with a speed responsive device associated with the engine so that the engine ignition circuit will be interrupted when a predetermined preset engine speed is exceeded.

Another object of the invention is to provide an electric switch associated with a speed responsive meter in which the switch may be adjusted so as to be actuated under variable speed conditions.

A further object of the invention is to provide a safety switch for engines in which the presetting mechanism is completely contained within a speed responsive meter. a

A still further object of the invention is to provide a switch for controlling excessive speeds in engines which is inexpensive to manufacture, simple to use, and which is completely effective in its action.

Other objects and advantages will become apparent in the following specification when considered in the light of the attached drawings, in which:

Figure 1 is a fragmentary front elevation of a safety switch constructed in accordance with the invention.

Figure 2 is an enlarged fragmentary side elevation of the invention shown partly in section and partly broken away for convenience of illustration.

Figure 3 is a circuit diagram illustrating the method of wiring the invention to an engine.

Figure 4 is a fragmentary vertical cross-section taken along the line 4-4 of Figure 2, looking in the direction of the arrows.

Figure 5 is an exploded perspective view of the attachment elements of the invention.

Figure 6 is a fragmentary side elevation of a modified form of the invention shown partly broken away and in section for convenience of illustration.

Figure 7 is a fragmentary front elevation of the modification illustrated in Figure 6.

Referring now to the drawings in detail wherein like reference characters indicate like parts throughout the several figures, the reference numeral 10 indicates generally an engine safety switch constructed in accordance with the invention.

The engine safety switch 10, referring particularly to Figures 1 through 5, is mounted on an instrument panel 11 which is mounted adjacent to the engine (not shown) to be controlled. The safety switch 10 includes a housing 12 of a conventional tachometer which is secured to the instrument panel 11 by means of a bracket 13. A flexible shaft 141- extends from a rotating portion of the engine (not shown) driving the tachometer mechanism (not shown) within the housing 12 in a conventional manner. A hand 15 is secured to the tachometer mechanism (not shown) and rotates to give a speed indication on a calibrated dial l6, referring particularly to Figures 1 and 2.

The calibrated dial 16 is mounted in the housing 12 in any conventional manner and the housing 12 is provided with a glass bezel 17 covering the hand 15 and dial 16 to prevent dirt and other foreign material from entering the housing 12. The hand 15 through its mounting, and the housing 12 is electrically grounded, as illustrated at 18 in Figure 3.

A switch structure, generally indicated at 19, is of the magnetic relay type previously patented to me. The switch 19 is mounted within the housing 12 adjacent the bezel 1'7 and is provided with a stationary contact 20 and a movable contact 21. The movable contact 21 is carried on an arm 22 which is spring biased to the position illustrated in Figure 2 with the contact 21 spaced from the contact 20.

An electro-magnet 23 is positioned within the switch 19 and is arranged to move a latch arm 24 to an unlatched position when the electro-magnet 23 is energized. The arm 22 is movable to a position with the contacts 22 and 20 in engagement and the upper end of the arm 22 secured by a detent 25 on the latch arm 24 by means of a push pin 26 mounted so as to extend through the bezel 17 by means of a threaded body 27 and a nut 28.

The bezel 117 is provided with a central bore 29 in which is journalled a pin St The pin 3ft, referring particularly to Figure 5, is provided with an externally threaded end portion 31, a slotted terminal end 32, a reduced mid-portion 33, an annular flange 3d, and an opposite end portion 35.

An arm 36 is provided with a hub 37 having a bore 58 therein. The bore 38 is engaged over the end portion with the hub 37 in contact with the flange 34 with the end portion 35 riveted as at 39, in Figure 2,, to secure the arm 36 to the pin 30 in fixed relation. A contact pin 40 isriveted to the outer end of the arm 36 extending through a bore 41 therein with the contact pin 41 projecting perpendicularly from the arm 36.

An arm 42 having a hub 43 is journalled on the pin 3% in contact with the side of the annular flange 34 opposite the arm 36. A washer 44 is likewise journalled on the pin 30 in contact with the hub 4-3 and in contact with the inner face of the bezel 17 with the pin 3t) extending through the bore 29. A split lock ring 45 is engaged over the pin 30 in the reduced area 33 thereof so as to lock the pin 30 in the bore 29 of the bezel 17 for rotational movement therein.

A washer 46 is engaged over the tubular metallic extension 47 projecting from a plastic knob 48. The tubular extension 47 is internally threaded for engagement with the externally threaded portion 31 of the pin 30, as best seen in Figure 2. The knob 48 has a bore 4-9 extending therethrough so that the slotted end portion 32 of the pin 39 is accessible.

The pin 30 can be readily turned within the bore 29 to rotate the arm 36 to any position about the dial 163 by engaging a screw driver in the slotted end 32 thereof. When the arm 36 has been adjusted to the desired position, the knob 48 is tightened on the threaded end portion 31 of the pin 30 locking the pin 30 against further adjustment.

Referring now to Figure 3, the circuit involved in the present invention is disclosed with a battery 5i) having one side thereof connected to ground 51. The opposite side of the battery 5ft is connected to the ammeter 52 and then through a fuse 53 to the stationary contact 20. The movable contact 21 is connected to the coil 54 which is wired to the distributor 55 in the usual manner.

One side of the electro-magnet 23 is connected to the movable contact 2t While the other side thereof is connected to pin 46 on arm 36. Thus it can be seen that when the hand 15 contacts the pin 40, the electro-magnet 23 will be energized from the battery when the contact 21 is in engagement with the contact 20. Energization of the electro-magnet 23 will swing the latch arm 24 downwardly releasing the contact arm 22 breaking the connection between the contacts 20 and 21 thus opening the circuit to the coil 5d and distributor 55. A contact Wire 56 extends from the electro-magnet 23 to additional safety switches operated by low oil, excess temperature, and similar emergencies.

Obviously, the arm 36 can be adjusted with relation to the dial to so that the hand 15 will contact the pin 40 at any desired preset speed.

Referring now to the modification illustrated in Figures 6 and 7, a safety switch it) is mounted in an instrument panel 11. The safety switch it) includes a tachometer housing 12 secured to the instrument panel 11' by means of a bracket 13'. A drive mechanism 14' extends to the housing 12 from a rotating part of the engine (not shown).

The safety switch it? is intended for use with engines already provided with magnetically operated switch 19, wherein the magnetically operated switch 19 is operated by pressure, temperature, or other means. A hand 15 is connected to and driven by the tachometer mechanism (not shown) Within the housing 12' and registers the speed of the engine (not shown) on a calibrated dial 16'. The tachometer hand 15 is grounded through the driving mechanism and the housing 12, for reasons to be assigned.

The housing 1?, is closed by a bezel 37 identical to the bezel 17. The bezel 17 is provided with a central bore 29'. A journal pin 30 identical to the preferred form of the invention is mounted in the bore 2.9 and has secured thereon members identical to those illustrated in the preferred form of the invention. The arm 42 of the preferred form of the invention, however, is replaced with an arm 42 which has a somewhat greater length than the arm 42 and to which is secured a wire 57 extending to a circuit similar to that illustrated in Figure 3.

The operation of the modification illustrated in Figure 6 is identical to that of the preferred form of the invention since the structures are for practical purposes identical.

Having thus described the preferred embodiments of the invention, it should be understood that numerous other structural modifications and adaptations may be resorted to without departing from the scope of the appended claims.

What is claimed is:

1. An adjustable safety switch comprising a meter housing, a meter hand journalled in said housing and electrically connected to said housing, a transparent bezel closing one side of said housing adjacent said hand, said bezel having a medial bore extending therethrough, a pin journalled in said bore, an annular flange fixed to said pin for engaging the side of said bezel adjacent said hand, said pin having an annular groove formed therein adjacent the side of said bezel opposite said flange, a split ring washed engaged in said groove and against the side of said bezel opposite said flange with said washer and said flange restraining said pin against axial movement in said bore, said pin having the end portion thereof opposite said flange threaded and terminating in a transverse slot, a lock knob having an axial bore extending therethrough threaded on the threaded end portion of said pin and adapted for clamping engagement with said washer, an electric contact arm fixed to the end of said pin opposite said slot and extending radially outwardly therefrom, and an electric contact member fixed to the outer end of said arm in laterally extending relation for electrical engagement with said hand on rotation of said hand.

2. A device as claimed in claim 1 wherein a second arm is supported by said pin and extends radially therefrom, and electrical wiring connects said second arm to an electric circuit, said first and second arms on said pin being in electrical contact with each other.

Rosenthal Sept. 10, 1940 Greenberg June 13, 1950 

